Multidomain biofilm control in a novel simulated microgravity reactor

Issues caused by unwanted microbial accumulation in spacecraft water systems must be addressed for successful spaceflight missions traveling much farther from Earth than the International Space Station (ISS). Biofilms have previously caused clogs in the ISS water recovery system, which required part replacement. The study presented here builds on previous research (Mettler and Peyton, 2025) to control biofilms in the ISS water system by evaluating three methods of biofilm control for their efficacy in a simulated microgravity biofilm reactor. This research aimed to model the ISS by using four direct isolates from the water recovery system, a medium designed to mimic the chemical composition of ISS wastewater, and simulated microgravity. Surface-associated biofilm formation and microbial aggregates in the bulk fluid were evaluated as they both pose concerns for clogging in spacecraft water systems. By the end of the 7-day experiment, no viable biofilm was detected on the surfaces in the reactor with an antifouling coating, no-phosphorus medium, and daily silver fluoride biocide dosing. This research marks a large step in accurately modeling the ISS water recovery system and exploring options for biofilm control in future spacecraft water systems.